replaced IAC... still having idle problems.

four.six · Aug 12, 2005

well guys, i replaced the IAC. but the RPMs are still acting funny. it mostly does it after down shifting when i press in the clutch. the RPMs drop to like 4 or 5 hundred, then shoot up to 11 or 12 hundred. then go back to idle at 800 (thats what i set it at with my tuner). sometimes, the car even dies (i look really cool when that happens). i think i could have a slight exhaust leak. when driving by curbs and walls i can hear a "pppsssssssssss" sound. i have tried many times, readjusting my X, to fix the leak. no luck on that. could this slight exhaust leak have something to do with my RPMs fluttering. or could it be some other problem?? thanks for the help guys.

four.six · Aug 12, 2005

anyone???

Jakes · Aug 13, 2005

Just a guess but if it was me I'd start looking for a vacume leak somewhere. Recheck all your connections and hoses for leaks cracks or splits.

four.six · Aug 13, 2005

Jakes said:
Just a guess but if it was me I'd start looking for a vacume leak somewhere. Recheck all your connections and hoses for leaks cracks or splits.

i have visually checked the all the hoses, and no signs of cracks or leaks. its only got about 29000 miles. maybe i will try that propane torch technique.... but is there any possible way that it could be the exhaust leak??

four.six · Aug 13, 2005

somebody HELP please!!!!

Kilgore Trout · Aug 13, 2005

1) Take off the MAC CAI
2) Install your stock intake with freshly cleaned MAF
3) Reset PCM
4) Thank Kilgore

jstreet0204 · Aug 13, 2005

Yes an exhaust leak can cause the problem you are describing if it is close to the front o2 sensor.

four.six · Aug 13, 2005

jstreet0204 said:
Yes an exhaust leak can cause the problem you are describing if it is close to the front o2 sensor.

im not sure where the leak is but its pissing me off. im gonna take it to an exhaust shop tomorrow to get the leak fixed.

four.six · Aug 13, 2005

Kilgore Trout said:
1) Take off the MAC CAI
2) Install your stock intake with freshly cleaned MAF
3) Reset PCM
4) Thank Kilgore

so, ur telling me the MAC CAI is what is causing that?? i didnt think of that. so the MAC CAI is no good? well hopefully i can find my stock intake and air silencer. how do i reset the PCM?? should i install factory tune before reseting the PCM?? and what CAI do you suggest??

forpit2000gt · Aug 13, 2005

four.six said:
so, ur telling me the MAC CAI is what is causing that?? i didnt think of that. so the MAC CAI is no good? well hopefully i can find my stock intake and air silencer. how do i reset the PCM?? should i install factory tune before reseting the PCM?? and what CAI do you suggest??

no need for the air silencer, but the Mac CAI can go and will do notheing but help.
Anytime you have a problem like this ,I would put stock tune back in and parts and work your way back a step at a time to correct the problem. You could just have a leak behind the MAF. I went with a C&L inlet pipe and straight K&N for my best results. I do still have a pretty , shiny MAC in a box somewhere.

four.six · Aug 13, 2005

forpit2000gt said:
no need for the air silencer, but the Mac CAI can go and will do notheing but help.
Anytime you have a problem like this ,I would put stock tune back in and parts and work your way back a step at a time to correct the problem. You could just have a leak behind the MAF. I went with a C&L inlet pipe and straight K&N for my best results. I do still have a pretty , shiny MAC in a box somewhere.

well crap, there goes $150..... i guess i will invest in the inlet pipe and k&n.

stangman16 · Aug 13, 2005

it's strange, my car does this too.. and I've changed the IAC also - when it would start but die instantly after letting off the gas. So, I guess I'm leaning towards a vacuum leak. Seems like it does it only after I get the car stopped.

stimmler · Aug 14, 2005

mine too but, I noticed it only does it with the A/C on. So I have no idea either. I also tried to replace the IAC with no luck. I would say vacuum leak also, which is what I am trying to find on mine.

four.six · Aug 14, 2005

stimmler said:
mine too but, I noticed it only does it with the A/C on. So I have no idea either. I also tried to replace the IAC with no luck. I would say vacuum leak also, which is what I am trying to find on mine.

my car does it regardless if the ac is on or not. i am really getting pissed off about this. the car died today as i was downshifting coming to a stop at a light. i almost hit the car infront of me cause of no power brakes.

forpit2000gt · Aug 14, 2005

when was the last time your car ran and idled fine?What was the last thing you did before it started this? Do you know how to check for leaks? Did you run any different fuels or cleaners through the system?

Shiroelex · Aug 14, 2005

I solved funky idle problems in my old 83 BMW 633CSI by replacing the front O2 sensor. Something I'd reccomend doing, if all else fails. Another thing it could be, but not very likely, would be your TPS. I've personally only seen one be the culprit my entire life, and that would typically show up as a MIL code. Check to make sure there is no air leaks at all between the MAF and the TB. I've seen some CAIs that leak around the grommet that the IAC plugs into, and causes all kinds of crap to happen. One last thing I can think of; I've seen some parts store sell an IAC that looks and fits correctly, but was the wrong part. This was on a 2.0 Escort I was working on, but I'm sure it could happen with a 4.6 just the same. Good luck!

03MGT · Aug 14, 2005

four.six said:
well guys, i replaced the IAC. but the RPMs are still acting funny. it mostly does it after down shifting when i press in the clutch. the RPMs drop to like 4 or 5 hundred, then shoot up to 11 or 12 hundred. then go back to idle at 800 (thats what i set it at with my tuner). sometimes, the car even dies (i look really cool when that happens). i think i could have a slight exhaust leak. when driving by curbs and walls i can hear a "pppsssssssssss" sound. i have tried many times, readjusting my X, to fix the leak. no luck on that. could this slight exhaust leak have something to do with my RPMs fluttering. or could it be some other problem?? thanks for the help guys.

My upr x-pipe does the same exact thing you discribed. I was about to put my stock midpipe back on... But im gonna try this before I take it off http://www.ninosport.com/index.asp?PageAction=VIEWPROD&ProdID=281 because im not using a gasket on the passenger side... Did you put the gasket between the header and the midpipe?? Or no? If so and it still leaks im throwing my upr x-pipe out..

COBRA90GT · Aug 14, 2005

FWIW - you can reset the PCM (computer) by disconnecting the battery. Just remove the negative cable terminal - you can leave it unhooked overnight if you are really paranoid. Meh.

I would also ditch the MAC CAI because it utilizes metal piping - which retains extra heat. That's not really ideal for a CAI, might want to look into a Home Depot version (do it yourself) or pay for another aftermarket version such as the JLT (seems to be quite the rage lately). As long as the intake tract is rubber/plastic, it will help to keep your inlet air temperatures somewhat lower (compared to a metal tract, such as the MAC design).

Also, was your car suffering from "the stall" prior to using the tuner? Which tuner are you using? I remember other people suffering from weird glitches like stalling and/or poor idling due to an aftermarket tuner (handheld tuners, that is).

Try running the car without the tuner, resetting the PCM, and allow for several drive cycles to see if the drivability problem can be resolved. In the meantime, give yourself plenty of stopping distance while in traffic - suddenly losing power in traffic is a safety hazard.

G'luck with the troubleshooting.

Ghostface · Aug 14, 2005

four.six said:
my car does it regardless if the ac is on or not. i am really getting pissed off about this. the car died today as i was downshifting coming to a stop at a light. i almost hit the car infront of me cause of no power brakes.

I just had this problem the other day for the first time also. Right after I started the car and went down the street to a complete stop, the car just died while in neutral. It seems like it could've been a dangerous situation like yours if it happend during the wrong time. The only thing I can think of that has changed with my car recently is I changed the mufflers about 1000 miles ago.

Someone got the true answer to this??

dhrusk1 · Aug 14, 2005

I have a stock 2000 gt with 38000, and it almost dies sometimes too. Basically, when I come to a light RPM drops just below 500, and then raises up to almost 1000 before settling down to the normal idle.

So, I don't think it is the mods that are causing this problem, but I am installing mac longtubes, a prochamber, and densecharger cold air kit so I will let you guys know if it gets worse.

I would really like to fix this problem, how much are o2 sensors, I might as well change them as long as they are not too expensive?

replaced IAC... still having idle problems.

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